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Proceedings Paper

Dual-energy digital mammography for calcification imaging: theory and implementation
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Paper Abstract

Small microcalcifications essential to the early detection of breast cancer may be obscured by overlapping tissue structures. Dual-energy digital mammography (DEDM), where separate low- and high-energy images are acquired and synthesized to cancel the tissue structures, may improve the ability to detect and visualize microcalcifications. The investigation of DEDM began with a signal-to noise ratio analysis to estimate and relate the noise level in the dual-energy calcification signals to the x-ray spectra, microcalcification size, tissue composition and breast thickness. We investigated various inverse-mapping functions, both linear and non-linear, to estimate the calcification thickness from low- and high-energy measurements. Transmission (calibration) measurements made at two different kVp values for variable aluminum thickness (to simulate calcifications) and variable glandular-tissue ratio for a fixed total tissue thickness were used to determine the coefficients of the inverse-mapping functions by a least-squares analysis. We implemented and evaluated the DEDM technique under narrow-beam geometry. Phantoms, used in the evaluation, were constructed by placing different aluminum strips over breast-tissue-equivalent materials of different compositions. The resulting phantom images consisted of four distinct regions, each with a different combination of aluminum thickness and tissue composition. DEDM with non-linear inverse-mapping functions could successfully cancel the contrast of the tissue-structure background to better visualize the overlapping aluminum strip. We are currently in the process of translating our DEDM techniques into full-field imaging. We have designed special phantoms with variable glandular ratios and variable calcification thicknesses for evaluation of the full-field dual-energy calcification images.

Paper Details

Date Published: 6 May 2004
PDF: 10 pages
Proc. SPIE 5368, Medical Imaging 2004: Physics of Medical Imaging, (6 May 2004); doi: 10.1117/12.534115
Show Author Affiliations
Srinivas Cheenu Kappadath, Univ. of Texas/M.D. Anderson Cancer Ctr. (United States)
Chris C. Shaw, Univ. of Texas/M.D. Anderson Cancer Ctr. (United States)
Chao-Jen Lai, Univ. of Texas/M.D. Anderson Cancer Ctr. (United States)
Xinming Liu, Univ. of Texas/M.D. Anderson Cancer Ctr. (United States)
Gary Whitman, Univ. of Texas/M.D. Anderson Cancer Ctr. (United States)

Published in SPIE Proceedings Vol. 5368:
Medical Imaging 2004: Physics of Medical Imaging
Martin J. Yaffe; Michael J. Flynn, Editor(s)

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